Backflow prevention assemblies, devices, and/or methods are utilized on water supply piping to protect against hazards caused by backpressure or back-siphonage conditions that could cause pollutants or contaminants to backflow into the public water supply and/or the water user's system.
Under current Oregon Administrative Rule 333-061-0070, Department-approved testable backflow prevention assemblies shall be assemblies approved by the University of Southern California (USC) Foundation for Cross Connection Control and Hydraulic Research.
Assembly approvals listed are individually dated and valid within 3 years of the current date, specific to manufacturers, model numbers, piping sizes, installation orientations, and attached shutoff valves. Detector type assemblies are additionally listed with the specific approved bypass meter(s). The list includes the four general types of testable backflow prevention assemblies:
- Reduced Pressure principle backflow prevention assemblies (RP) and the related Reduced Pressure principle-Detector backflow prevention Assemblies (RPDA),
- Double Check valve backflow prevention assemblies (DC) and the related Double Check-Detector backflow prevention Assemblies (DCDA),
- Pressure Vacuum Breaker back-siphonage prevention assemblies (PVB), and
- Spill Resistant Pressure Vacuum Breaker back-siphonage prevention assemblies (SVB).
Non-Testable Backflow Prevention Devices
Atmospheric Vacuum Breakers
(AVB) are approved under Oregon Plumbing Specialty Code as listed with the ASSE Seal Program. The American Society of Sanitary Engineering (ASSE)
Seal Program lists approved manufacturers and uses, for example, the standard designation of 1001 for pipe applied AVB (example: irrigation systems) and 1011 for hose-type connection AVB.
An approved air gap is a method of backflow prevention that means the physical separation between the end of the water supply pipe (example: faucet) and an open vessel (example: sink). Approved air gaps are generally at least twice the diameter of the supply piping, in no case less than 1 inch (2.54 cm) and are in accord with Oregon Plumbing Specialty Code.